title: Breastfeeding, retinoids, and postpartum depression: a new theory.
abstract: Postpartum depression (PPD) is an international public health problem affecting at least 1 in 8 mothers. Known risk factors include: giving birth to a preterm or low birth weight infant, babies with greater symptoms of illness at age 4-6 weeks, formula feeding, younger maternal age, smoking, and fatigue. Prolonged breastfeeding is associated with a reduced risk of PPD but the mechanisms are not well understood. Interventions for PPD focusing on psychosocial risk factors have been largely unsuccessful, suggesting that the condition has a mainly biological basis. The hypothesis proposed for consideration is that breastfeeding protects against PPD by maintaining endogenous retinoids (vitamin A-related compounds) below a threshold concentration. In fact, breast milk is rich in retinoids; pregnant women accumulate retinoids in liver and breast in preparation for lactation; there is increasing evidence that retinoids in higher concentration are associated with cognitive disturbances and mood disorders, including depression and suicide; and prolonged lactation reduces maternal stores of retinoids. Consistent with this hypothesis, it is estimated that an amount of vitamin A is transferred from mother to infant during the first six months of exclusive breastfeeding equivalent to 76% of a dose known to cause acute vitamin A poisoning in an adult. Breastfeeding may thus have evolutionary-adaptive functions for both mother and infant, transferring vital nutrients to an infant unable to feed itself, yet at the same time providing a natural means of reducing potentially toxic concentrations of retinoids in the mother.
authors.affiliation: Behavioral and Environmental Health, School of Health Sciences, College of Public Service, Jackson State University, 350 West Woodrow Wilson Drive, Room 229, Jackson, MS 39213, USA. amawsn@gmail.com
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Mawson
authors.forename: Wang
authors.initials: W
authors.lastname: Xueyuan
mesh_terms: D000328:Adult; D000818:Animals; D001942:Breast Feeding; D019052:Depression, Postpartum / Q000453:epidemiology* / Q000378:metabolism* / Q000517:prevention & control; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008413:Mastitis / Q000523:psychology; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D009034:Mother-Child Relations; D011247:Pregnancy; D047928:Premature Birth; D012176:Retinoids / Q000032:analysis / Q000378:metabolism*; D014801:Vitamin A / Q000032:analysis / Q000378:metabolism
chemical_list: D012176:Retinoids; D014801:Vitamin A
keywords: Breastfeeding; Depression; Liver; Mastitis; Postpartum; Retinoids